🧭 Reference material to refresh what you already studied for your CoC — not a substitute for the
official IMO COLREGs text or your ship's own bridge procedures.
📖
COLREGs, Plain-Language
All 41 Rules, grouped by part, with a link to the official IMO text.
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Lights & Shapes
Pick a vessel status and see its lights and day shapes — with a quiz mode.
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Buoyage
IALA Region A and B lateral marks, cardinal marks, and the other special marks.
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Signal Flags
All 26 International Code of Signals letter flags and what each means alone.
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Passage Calculators
Speed/distance/time, great-circle distance, ETA across time zones, and unit converters.
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